Many types of input devices are presently available for performing operations in a computing system, such as buttons or keys, mice, joysticks, trackballs, trackpads, touch screens and the like. Touch screens can include a touch sensor panel, which can be a clear panel with a touch-sensitive surface. The touch sensor panel can be positioned in front of a display screen so that the touch-sensitive surface covers part of all of the viewable area of the display screen. Touch screens can allow a user to make selections and move a cursor by simply touching the display screen via one or more fingers or a stylus. In general, touch screens can recognize the touch and position of the touch on the display screen, and a computing system can interpret the touch and thereafter perform an action based on the touch event. Trackpads can also include a touch sensor panel, but the panel need not be transparent because no display screen is involved.
With touch screens and trackpads as described above, a number of gestures can be recognized by a computing system processing the obtained images of touch. However, it can be difficult for a user to remember the gestures that can be performed, particularly if the available gestures are dependent on the application being executed.